And in 2014, a 35-year-old Swedish woman became the first person to give birth using a donated uterus, from a 61-year-old friend of hers. In that case, the mother went through in-vitro fertilization (IVF) before the surgery and froze her eggs to use once she got her donor uterus.

But the trial at the Cleveland Clinic will be the first in the US, and the announcement set off a media firestorm, including a widely shared article in The New York Times.

Unlike IVF, however, uterus transplants will only be an option for a small number of women in the US — those who don’t have a uterus because they were born that way (a condition that affects about 1 in 4,500 girls) or because they had a hysterectomy. Around half a million women get hysterectomies in the US every year, according to the American Congress of Obstetricians and Gynecologists.

Transplants are also a costly and complicated procedure, even after getting over the initial hurdle: finding a donor. Transplanting any organ can be difficult since the body identifies transplants as foreign objects that it must attack. So patients often have to be put on drugs to suppress their immune systems to prevent this from happening. The same happens with uterus transplants; the woman’s body recognises the transplant as an intruder.

In the successful transplants in Sweden, researchers were able to prevent the body from rejecting the transplanted uteruses, though the women have to keep taking anti-rejection drugs even during pregnancy. Nine women in that trial received uterus transplants, but two had to have them removed because of a blood clot or infection. Four have successfully given birth, and one more is currently pregnant, The Times reports.

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Perhaps the most remarkable aspect of the procedure in the US is that doctors plan to remove the uterus after the woman gives birth to “one to two babies,” the Cleveland Clinic writes. That means the women won’t have to be on immunosuppressive drugs for their whole lives.

Uterus transplants have a long way to go before they become reliable, safe, and effective. It is also unclear how much the procedure would cost if and when it become clinically available. But they may someday make it possible for women to get pregnant who currently have no options for doing so.

“Although there appears to be potential,” Dr. Tommaso Falcone of the Cleveland Clinic said in a press release, “it is still considered highly experimental.”